Hemi MDS
I was wondering if anyone other than me absolutely hates the MDS system in their Hemi engines. Does anyone know how to disable it without having to by a Diablo Predator tuner? I know you can cut and cap the wire, but then the check engine light will stay on. Does anyone have any solutions for me?
It shuts down some of the cylinders for better fuel mileage while cruising. Once throttle is applied again all cylinders begin firig again for full power.
MDS stands for Multi Displacement System, which when at highway speed will shut down to use only four cylinders instead of all 8 to save on fuel consumption. When you step on the gas to climb a hill or pass another vehicle or just to hear that HEMI Roar, the other 4 cylinders will automatically kick back in. I love my HEMI with MDS.
If you want to disable it, just put your truck into O/D off or Tow-Haul Mode, then it will stay running 8cylinders.
i agree mds sucks, if you have a sct vcal tunner you can disable it it is a trs2431 code and it will disable the mds. and you will not have a engine light come one if u do it correctly. sct.com will walk you through the steps, hope that helps
i just bought the diablo predator and it does not disable the mds and if anybody knows how to make it disable mds let me know please.
i don't understand the problem here...my charger literally gets 29 MPG hwy with a little city thrown in if my foots not in it...you absolutely CANNOT feel the mds turn off and on...you're either feeling the overdrive kick off and on or you have a miss or timing issue or something...the computer disables mds in less time than it takes for the next deactivated cylinder to finish the stroke it's on.
well i dont know why people havnt caught onto this but, you can take it back to the dealer and for a small price they can just reprogram the computer and turn the MDS off it beats a predator tuner which are just about useless.
like i said in my first post!! the sct xcal tuner will disable mds if that is what your wanting to do.
I have to run my truck in tow/hual mode. I guess the 35's confuse the computer into switching the mds on at any speed
my mds turns on when ever im off the gas . even if you are going 30 mph . its a pain . i was thinking it was just me then i took a ride in 3 other 2010 rams at my dealership and they were all the same. i think im going back to have it turned off . my milage is just a little better with it on but not that good. other then that i love the truck
Soory, but I just don't get it.......if you put your foot in it does it go like a "raped Ape"? Mine will. What's the big deal, so it "vibrates" a bit.....so what. I have found that it will improve the fuel milage, by how much, I really don't care....IT'S A TRUCK!!
I have a 2009 Ram 1500 with the mds. It is constantly kicking in at low speed and periodically it will kick on while I'm attempting to accelerate. From time to time it lurches as the computer figures out to turn it back off. This has been happening since I acquired the vehicle new May 2009. There is a TSB out there that says to reprogram and that will "smooth out the transition." Had it done, worked a while, then back to the same. Like others I have not found that the gas savings are worth the hassle. Its a V8. I'll pay for the gas. If I want better mileage I'll buy a civic. Dealership was not helpful at all.
I never had a problem with the MDS untill I installed a performance exhaust on my '08 Hemi sport. It sounds kick-ass on 8 cylinders, but sounds like a UPS truck on it's last legs when in 4 cylinder mode. One friend asked me what was wrong with my truck, and if it was going to make it. Tow-Haul, and O/D Off kick it back to eight cylinders, but I want to be able to use O/D when cruising so I am most likely going to sacrifice a little fuel, and disable it.
Recently bought a 2011 Grand Cherokee Limited---between 30-65 mph while maintaining speed or slightly accelerating, engine misfires/hesitates frequently. Service Dept can't find anything wrong---service manager rode with me and felt the misfires---he stated that it had something to do with the cylinders shutting down to save gas and then firing back up for more power. Maybe so but this should not be doing this as much as it is. terribly annoying after I spent so much money on it. Filed complaint with Jeep customer service in detroit. they contacted the service manager who rode with me. they can't do anything unless they find something wrong on the computer---This is nonsense---Something is wrong with this hemi engine and probably with others---anyone else experiencing this problemChrysler customer service . After reading these posts I guess it is the MDS----I hate it--I will try turning it off with the haul.tow option---Had i known it was going to do this I would never have bought it.
I just bought my third Hemi with MDS on a 2011 RAM 1500 truck. Mine doesn't misfire but when the MDS kicks in the entire truck vibrates. Best gas mileage is 15 to 16 mpg. I agree something is wrong here and I hope the dealer can correct it before I go broke putting gas in it. I hate driving it thats for sure.
What octane fuel are you guys using? I had issues when I ran 87 and occasionally 89. Ran the best on 91. Even 93 seemed to cause issues with mine. It was really weird. But when I used 91 it ran perfect and I got 24 mpg hwy in my 300C.
This is direct from the chat with the Ram Hemi Engineers. To disable the MDS, put your shifter from D to 5 (as displayed on the EVIC or cluster). With the console shifter, this is just one hit to the left. With the column shifter you need to push the +- button - one time. Your trans will still shift up and down automatically through all the gears. Tow/haul button is not the correct method.
I have a 2008 Dodge Ram 1500 4wd with a column shifter... The display only has 1, 2, and D. There is not a +- button. Is there any way I can disable the MDS. Also, if this is such a customer issue, why not just disable the MDS feature when a certain throttle is applied???
The diablosport predator for one is awesome if done right. installed one on my 07 ram hemi and holy p1q490r!!!!! huge difference. But havent figured out how to disable the MDS either. I cant stand it. I have a magnaflow exhaust, I can hear it and feel it. I dont care about mileage, its a truck with a hemi!!! If I wanted mileage I would have bought a 4 cyl honda!!!
Wow, wish I had known about "disabling the MDS before I sold my 2011 (after owning 4 months) piece of junk Ram..it was horrible, completely unrefined...and just made driving it miserable...all the reviews are "rave"...I think people have "lowered their standards".
I love the Ram, just hate the MDS! wish I knew how to disable it.
I have the diablo sport predator, I still dont see anyway to disable it. I think when I disable the traction control, it disables it, But it also disables the cruise control, and alot of idiot lights come on. But hang on!!!!!
Boy, after reading all of these posts, I am somewhat relieved that I am actually not "crazy". When I contacted the dealer about my distaste for the "Gaspin Aspen", they said they didn't know what I was talking about. The GM truck I drove in '08 had the MDS and it was completely seamless...you never knew that they had tweeked the engine at all...ever! When I wanted to get up a hill with the pathetic excuse for engineering excellence (the Ram) my Hemi would gasp as if it was cutting out completely and then kick in...hated driving this gas sucking hunk of metal.....some "gas savings" City 12 Hwy 17....and I sold it after 6 months....Nice riding truck, that's it.............buy GM
I have a 07 HEMI Charger, I hate MDS. I have experienced the same lag or miss at highway speeds. It is not that noticeable, but it is there a slight bump or hesitation. I turned off the MDS with my predator tune and it runs like a V8 should now. I am about to go on a 10 hour trip and I believe I will turn it on again to see if I get any real gas savings. I will try the manual 5 speed option other than D as well. That was a good note for the none predator group out there for a manual fix.
MDS does shut down when in 5, but then the engine is reving higher at highway speeds. This system is just another liberal greenie weenie stupid attempt to dupe the public. There has to be a program to shut it down in 6th gear
Strange thing is - I had a 09 Ram with HEMI and MDS and it was completly seamless. Now have a 2012 and it is terrible with the vibration and low harmonic " buzz" when in 4 cyl mode and it goes imnto 4 cyl as low as 30 mph. I also had a 2005 Ram with a HEMI of course without MDS and the MPG is the same with or without the MDS. I have started driving my 2012 in 5th gear mode on the auto stick and it has not dropped the MPG even 1/10th per gallon - no differance at all and smooth as a whistle in straight 8 cyl all the time.
Dealer told me it was not possible as it is an inherit part of the engine management computer. I have a very good relationship with them as it is a very small town dealer and trust and believe them. have bought 5 vehicles over the years from them.
to disable the MDS on 2009+ Hemi Ram 1500, with gear selector in drive drop out of OD, press toggle +- both buttons at the same time, will drop to 1, then just select highest gear to allow trans to up & downshift. this must be done everytime upon starting vehicle. works great. just don't complain about the mpg.
HemRam09- I have run my 2012 crew cab in 6th Vs the eco mds mode on same stretches of highway under the same conditions for thousands of miles as I travel a lot for work and it did not drop the fuel mileage one bit - not even a 10th of a mpg. not sure why as the mds is supposed to get you better mileage, but I could not live with the low hum/buzz/vibration when in mds/eco mode - it was very annoying. When driving at 72 mph ( speed limit 70) with the cruise on, I get 20.2 - 20.4. When I am in a slower state, say 60 mph, I get close to 22 mpg. These are not short trips as my average trip is 380 miles one way. In the city I average about 14.3 - 15.4 mpg. I burn regular 87 octane gas just fine, but I only use ethanol free gas - I will not use gas that has ethanol in it.
so unless you have a 2009 or newer you cant disable you MDS....... thats %$&@ing bull#$@! there has to be a way.
Ok try to keep up. prior to 2009 select tow/haul 2009 & up with truck running but move gear selector to Drive then press +/- select 4 then press +/- at the same time(its tricky) moves up to 5 then drops down to 1, then select whatever gear you want and as long as you dont turn the key off mds will stay off.
I have a 2006 Jeep Commander with a Hemi. I hate the MDS feature, I feel constant hesitation at many different speeds. I am just scared my transmission is going to fail. Can someone put my mind at ease, that its just going to fell like a shitty ride and not put me on the side of the road!
Ok guys I don't know if this will help i have a 2012 ram hemi i have a miss that i feel when idle i know that is the mds system and that great vibration and shutter that every one has bugs the crap out of me. All i do is when running around town i use the auto stick put in 5 gear and shift fine from 1 to 5 no mds working . and on freeway same but put in 6th no mds have not noticed any drop in fuel mpg when you are traveling at hwy speeds 6th gear only kicks in at 65 to 70 = anyway anything over 75+ eco mode does not come on unless going down hill . The around town driving is where i really notice the eco shutter/miss fire
Also Guys and Gals , Most cars/trucks now days have a self learning computer in them that programs the motor to the way you drive and if you did what i did test driving the truck the way i did seeing what the hemi could do and about the 1st week i owned it the truck learned that i am heavy on the gas peddle and programed the motor for best performance not mpg . the only way to fix this is pull the + term off battery and wait for 30 min or so for back up battery in computer to die reconnect the term and drive it like you want the best mpg no hard accel or letting the 390 hp loose do this for about 10 to 20 miles and then the computer will learn your driving habbits i did this when i noticed i could only get 15mpg from houston to la .The first trip i took in it when i was there i reset the computer and on my way home i got 18 to 20 .. Hope this helps
Hey all... note from Canada, Pretty good thread you have going here. I have a 2010 ram 1500 4x4 with a Hemi. I don't have a problem with normal driving... Where I notice the hesitation most is when accelerating and turning .... like when you're turning left at a set of lights and attempting to accelerate through the turn. I had noticed this hesitation on both the Ram 1500 when testdriving and on the Chevy Silverado with the 6.2 liter. The silverado had it worse. STill bought the ram. I'm not positive if it's the MDS system or if the truck is grabbing the next gear too early or.... if one of the nanny's is kicking in thinking that the truck is gonna rollover or something. I have been driving with the traction control disabled most of the time recently(I realize it's not totally disabled but at least you can goose the tires a bit if you want). Any ideas? I haven't been able to catch the hesitation while viewing the tach. As in a previous post the computer may be learning about my heavy foot and not hesitating as much now....or perhaps it's just hesitating more when i haven't turned off the traction control Long post i know.... what do you think? James
James, mine does the same crap it's the way the transmission shifts and it prob has something to do with the mds system to i wish they had never put that crap in the truck the gas miliage in my truck is about 1 mpg different between on and off its a truck with 395 hp I'd I wanted great gas miliage I would have brought a car . With the six speed trans that mine has the shift points are very close almost to the point where it shifts to fast and cause the motor to lug around my truck is only in first gear for about 3 seconds after start off and shifts to second as I am turning . And shifts pretty hard from first to second I have actually caught a chirp from the tires during the shift and from second to third I notice it a lot more with the 35' tires I have on mine .Hope this helps !
I think you're right Kenneth. Too many nannies in the truck. It's not as bad with the traction control off. I did try mid grade fuel but that made no difference. I guess I just have to keep my foot in it so it stays in the lower gear....ha!
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